Indoor unit of air conditioner

ABSTRACT

This invention relates to an air conditioner having an air inlet at its upper portion. The heat exchanger ( 4 ) includes multiple plate fins ( 1 ) arranged in parallel so that air flows therebetween, and heat transfer tubes ( 2 ) perpendicularly inserted into the plate fins ( 1 ) and arranged perpendicularly to the air flow direction through which working fluid passes. The heat exchanger ( 4 ) includes a lower front heat exchanger ( 4   a ), an upper front heat exchanger ( 4   b ), and a rear heat exchanger ( 4   c ) separately produced and arranged to surround the circulating fan ( 5 ). The air pressure loss of the lower front heat exchanger ( 4   a ) is set to be smaller than the air pressure losses of the other heat exchangers.

FIELD OF THE INVENTION

The present invention relates to an indoor unit of an air conditionerthat uses a fin-tube type heat exchanger to exchange heat between fluidsuch as air.

DESCRIPTION OF THE RELATED ART

An indoor unit of a conventional air conditioner having a fin-tube heatexchanger is disclosed in Japanese Unexamined PatentApplication-Publication No. 11-183077 (page 3 of the specification andFIGS. 1 and 2). Grilles serving as air inlets are provided on the topand front sides of the indoor unit, respectively. Louvered portionsprovided in a heat exchanger used in the indoor unit are partly removedin order to efficiently drain condensed water when the heat exchanger isused as an evaporator.

In another conventional heat exchanger disclosed in Japanese UnexaminedPatent Application Publication No. 2000-179993 (page 3 of thespecification and FIGS. 1 and 2), in order to enhance the heat exchangeperformance without reducing the draft resistance, louvered portions inthe first row on the windward side are provided on only one of the frontand rear sides of each plate fin, and louvered portions in the secondrow are provided on both the sides.

SUMMARY OF THE INVENTION

In the air conditioner disclosed in the former publication, no louveredportion is provided on the surface of a fin at an uppermost frontportion in a lower heat exchanger so that condensed water flows downfrom an upper heat exchanger to a drip pan at a lower portion throughthe fins without being concentrated at the upper ends of the fins. Whilethis indoor unit has two air inlets disposed at different positions, ina indoor unit having only one air inlet on the upper side, the windvelocity at the lower heat exchanger is insufficient, and the fan inputincreases.

When the fins of the heat exchanger disclosed in the latter publicationare used in a heat exchanger of a similar air conditioner having only anupper air inlet, a sufficient wind velocity is not obtained at the lowerheat exchanger because of the louvered portions provided in the firstand second rows, and the fan input increases. Moreover, the louveredportions are provided on both sides of the fins in the second rowTherefore, when air flows from the heat exchanger into the fan, it isseparated by blades in the fan, and the fan input increases.

Accordingly, the present invention has been made to overcome the aboveproblems, and an object of the invention is to provide an indoor unit ofan air conditioner having a heat exchanger that ensures a sufficientwind velocity, that prevents the fan input from increasing, and thatachieves a high heat transfer performance.

Another object of the present invention is to provide an indoor unit ofan air conditioner having a heat exchanger that enhances assemblingefficiency.

In order to achieve the above objects, according to an aspect, an indoorunit of an air conditioner according to the present invention includesan air inlet, a plurality of fin-tube type heat exchanger each havingheat transfer tubes extending through stacked plate fins, a fan, an airpassage, and an air outlet. The fin-tube type heat exchangers arearranged to surround the fan. The air pressure loss of an adjacent heatexchanger disposed adjacent to the air inlet, of the fin-tube type heatexchangers, is larger than the air pressure loss of a remote heatexchanger that disposed farther from the air inlet than the adjacentheat exchanger.

In the indoor unit of the present invention, the air pressure loss ofthe adjacent heat exchanger disposed adjacent to the air inlet is largerthan the air pressure loss of the remote heat exchanger disposed fartherfrom the air inlet than the adjacent heat exchanger. Therefore, asufficient wind velocity can be obtained at the remote heat exchanger,the fan input is not increased, and a heat exchanger having a good heattransfer performance in heat exchanging is provided.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of an indoor unit of an air conditioneraccording to a first embodiment of the present invention;

FIG. 2 is an explanatory view showing air flows in the indoor unit shownin FIG. 1;

FIG. 3 is a characteristic graph showing the relationship between thepressure loss and the air volume in a fan of the indoor unit shown inFIG. 1;

FIG. 4 is a cross-sectional view of a first modification of the firstembodiment;

FIG. 5 is a cross-sectional view of a second modification of the firstembodiment;

FIG. 6 is a cross-sectional view of a third modification of the firstembodiment;

FIG. 7 is a cross-sectional view of a fourth modification of the firstembodiment;

FIGS. 8A to 8C are sectional views of plate fins of a heat exchanger inthe fourth modification in FIG. 7;

FIGS. 9A to 9C are cross-sectional views of plate fins of a heatexchanger in a fifth modification of the first embodiment;

FIG. 10 is a cross-sectional view of a sixth modification of the firstembodiment;

FIGS. 11A to 11C are cross-sectional views of plate fins of a heatexchanger in the sixth modification shown in FIG. 10;

FIG. 12 is a cross-sectional view of a seventh modification of the firstembodiment;

FIG. 13 is a cross-sectional view of an eighth modification of the firstembodiment;

FIG. 14 is a cross-sectional view of a ninth modification of the firstembodiment;

FIG. 15 is a cross-sectional view of a tenth modification of the firstembodiment;

FIGS. 16A and 16B are explanatory views showing air flows in the heatexchanger in the tenth modification shown in FIG. 15;

FIGS. 17A and 17B are an explanatory views showing air flows in the heatexchanger in the indoor unit of the first embodiment; and

FIG. 18 is a circuit diagram of a refrigerant circuit according to asecond embodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment

FIG. 1 is a cross-sectional view of an indoor unit of an air conditionerhaving a heat exchanger according to a first embodiment of the presentinvention, FIG. 2 is an explanatory view showing air flows in the indoorunit shown in FIG. 1, and FIG. 3 is a characteristic graph showing thepressure loss and the air volume in a blower of the indoor unit shown inFIG. 1.

In these figures, the indoor unit of the air conditioner of the firstembodiment includes an air inlet 7 of an upper grille, a heat exchanger4 provided on the upstream side of air flows to surround a circulatingfan 5, an air passage 6 defined by a casing for guiding air, whichpasses through the upper grille, the heat exchanger 4 and thecirculating fan 5, to an air outlet 17, a condensed-water receiver 19provided below the heat exchanger 4, and a housing including a frontpanel 8. In the indoor unit, air is mainly sucked from the upper side,and is blown toward the front lower side.

The heat exchanger 4 includes a lower front heat exchanger 4 asubstantially vertically standing at the lower front of the indoor unit,an upper front heat exchanger 4 b provided between the upper grille 7and the lower front heat exchanger 4 a and slightly tilted so as to makeits upper portion positioned backward and its lower portion positionedforward, and a rear heat exchanger 4 c provided to extend from the uppergrille 7 to the lower rear of the indoor unit and slightly tilted so asto make its upper portion positioned forward and its lower portionpositioned backward. These heat exchangers 4 a to 4 c are arranged tosurround the circulating fan 5.

The heat exchanger 4 is a fin-tube type heat exchanger including stackedplate fins 1, and heat transfer tubes 2 perpendicularly inserted intothe plate fins 1. The pitch Fp in the stacking direction, thickness Ft,and width L of the plate fins 1 are 0.0011 m, 0.0001 m, and 0.0254 m,respectively. The wind velocity Uf at the front face of the heatexchanger 4 (mean wind velocity of the entire heat exchanger) is 1.0m/s, and the distance Dp between the centers of the adjacent heattransfer tubes 2 is 0.0254 m.

The plate fins 1 in the lower front heat exchanger 4 a are flat 3without louvered portions. Each of the plate fins 1 in the upper frontheat exchanger 4 b and the rear heat exchanger 4 c has a plurality oftrapezoidal louvered portions 3. The upper front heat exchanger 4 b andthe rear heat exchanger section 4 c have the same shape, and areproduced in the same production line. The plate fins 1 of the rear heatexchanger 4 c are partly folded to form a folded portion 21 so that therear heat exchanger 4 c is placed inside a rear guider.

The lower front heat exchanger 4 a, the upper front heat exchanger 4 b,and the rear heat exchanger 4 c are not joined for the entire heatexchanger, but are separate from one another. Therefore, slit patternsof the heat exchangers 4 a to 4 c can be easily changed.

In FIG. 2, air flows in the heat exchanger 4, principally in the lowerfront heat exchanger 4 a are shown by the arrows. The air flows producea circulating vortex 9 in the circulating fan 5.

Air does not pass through the front panel 8. Therefore, in a case inwhich louvered portions are provided in the entire of the lower frontheat exchanger 4 a, as in the upper front heat exchanger 4 b and therear heat exchanger 4 c, the wind velocity near the lower front heatexchanger 4 a is much lower than near the other heat exchanger 4 b and 4c.

For this reason, the lower front heat exchanger 4 a does not havelouvered portions in the first embodiment. That is, the air pressureloss of the lower front heat exchanger 4 a disposed remotely from theair inlet 7, of the fin-tube type heat exchangers 4 a to 4 c, is set tobe smaller than the air pressure losses of the upper front heatexchanger 4 b and the rear heat exchanger 4 c disposed near the airinlet 7. Since the air pressure loss of the lower front heat exchanger 4a is smaller than those of the upper front heat exchanger 4 b and therear heat exchanger 4 c, the wind velocity on the lower side of the heatexchanger increases, and the intensity of turbulence generated aroundthe vortex in the circulating fan increases. In this case, the staticpressure in the vortex decreases, and the efficiency of the circulatingfan increases.

In this way, air does not pass through the front panel 8, and is suckedfrom the air inlet 7 of the upper grille, and the lower front heatexchanger 4 a has no louvered portions. Therefore, the front side of theindoor unit is visually simpler than in a case in which an air inlet isprovided on the front side, and noise can be reduced. Moreover, asufficient wind velocity can be ensured at the heat exchanger 4 adisposed remotely from the air inlet 7. This prevents the input to thecirculating fan 5 from increasing, and enhances the heat transferperformance of the heat exchanger.

FIG. 3 is a characteristic graph showing the pressure loss ΔP and theair volume Ga when the circulating fan rotates at a constant speed ofrotation. A solid line 10 a shows the characteristic of the circulatingfan when the lower front heat exchanger 4 a is provided with louveredportions 3, a broken line 10 b shows the characteristic of thecirculating fan 5 when the lower front heat exchanger 4 a is notprovided with louvered portions 3, a solid line 11 a shows the pressureloss characteristic of the heat exchanger when the lower front heatexchanger 4 a is provided with louvered portions, and a broken line 11 bshows the pressure loss characteristic of the heat exchanger when thelower front heat exchanger 4 a is not provided with louvered portions.

A black circle shows a unit operating point when the lower front heatexchanger 4 a has louvered portions, and a white circle shows a unitoperating point when the lower front heat exchanger 4 a has no louveredportions.

When louvered portions are not provided in the lower front heatexchanger 4 a, the pressure loss of the lower front heat exchanger 4 ais smaller than when louvered portions are provided. The fancharacteristic is shifted toward the side where the pressure loss isgreater. Since the unit operating point thus shifts from the point 12 ato the point 12 b, the air volume Ga increases at the same rotationspeed. That is, the air volume Ga increases with no louvered portions.

In addition, the rotation torque in the circulating fan 5 can bestabilized, and air rarely flows back between the upstream anddownstream sides of the circulating fan 5.

In a case in which the heat exchanger is used as an evaporator, whenlouvered portions are not provided in the lower front heat exchanger 4a, the drain efficiency for condensed water deposited on the plate fins1 increases and the pressure loss decreases in comparison with the casewhere the louvered portions are provided.

For the same air volume, when louvered portions are not provided in thelower front heat exchanger 4 a, the speed of rotation is lower than whenlouvered portions are provided. At the same speed of rotation, the airvolume greatly increases, and the heat exchange performance alsoincreases.

In the first embodiment, after the upper front heat exchanger 4 b andthe rear heat exchanger 4 c are produced in the same shape, the portionsof the plate fins 1 of the rear heat exchanger 4 c which are in contactwith the rear guider 18 are folded to form the folded portion 21.Therefore, the production line is simplified and the production cost canbe greatly reduced, compared with a case in which the upper front heatexchanger 4 b and the rear heat exchanger 4 c are produced in differentshapes.

FIG. 4 shows a first modification of the first embodiment. In the firstmodification, auxiliary heat exchangers 4 d and 4 e having no louveredportions are added to the heat exchanger 4 of the first embodiment. Theauxiliary heat exchangers 4 d and 4 e are provided, respectively, on theupper front heat exchanger 4 b and the rear heat exchanger 4 c disposedon the upstream side of air flows. In this case, advantages similar tothose of the heat exchanger 4 shown in FIG. 1 are provided, and theperformance of the heat exchanger is enhanced by the auxiliary heatexchangers 4 d and 4 e.

FIG. 5 shows a second modification of the first embodiment. In thesecond modification, the auxiliary heat exchangers 4 d and 4 e shown inFIG. 4 have louvered portions 3. In this case, advantages similar tothose of the heat exchanger 4 shown in FIG. 1 are provided, and theperformance of the heat exchanger is further enhanced by the auxiliaryheat exchangers 4 d and 4 e having the louvered portions 3.

FIG. 6 shows a third modification of the first embodiment. In the thirdmodification, at the lowermost end (in the direction of gravity shown byarrow “g”) of each plate fin 1 in the lower front heat exchanger 4 a, alouvered portion 3 is provided only on the most downstream side in therow direction of louvered portions (shown by the right arrow in thefigure). The upstream portion of the plate fin 1 is flat. Since the windvelocity at the most end and on the lowermost downstream side of theheat exchanger can be increased, advantages similar to those of the heatexchanger 4 shown in FIG. 1 can be provided.

When the louvered portion 3 is not provided on the most downstream side,a vortex having a low flow velocity is produced on the trailing side ofthe heat transfer tubes 2 in the air flow direction. This adverselyaffects the heat transfer performance, and increases noise in thecirculating fan 5. However, the existence of the louvered portion 3 onthe most downstream side can overcome these problems.

FIG. 7 is a cross-sectional view of an indoor unit as a fourthmodification of the first embodiment shown in FIG. 1. FIGS. 8A, 8B, and8C are sectional views of the heat exchanger shown in FIG. 7,respectively, taken along lines A-A, B-B, and C-C. This indoor unit isobtained by modifying the indoor unit shown in FIG. 1 in such a mannerthat a lower front heat exchanger 4 a has louvered portions 3. Moreover,in order to reduce the air pressure loss, the fin pitch ha between platefins 1 in the lower front heat exchanger 4 a is set to be longer thanthe fin pitches hb and hc between plate fins 1 in an upper front heatexchanger 4 b and a rear heat exchanger 4 c.

In this case, the pressure loss caused by air flow through the lowerfront heat exchanger 4 a is smaller than that through the upper frontheat exchanger 4 b and the rear heat exchanger 4 c, and the velocity ofthe air passing through the lower front heat exchanger 4 a increases.Consequently, advantages similar to those of the heat exchanger 4 shownin FIG. 1 can be provided.

FIGS. 9A, 9B, and 9C are sectional views of a heat exchanger in a fifthmodification of the first embodiment, respectively, taken along linesA-A, B-B, and C-C in FIG. 7, in a manner similar to that in FIGS. 8A,8B, and 8C.

In order to reduce the air pressure loss of the lower front heatexchanger 4 a, the height Sa of the louvered portions 3 of the platefins 1 in the lower front heat exchanger 4 a is set to be smaller thanthe heights Sb and Sc of louvered portions 3 of the plate fins 1 in theupper front heat exchanger 4 b and the rear heat exchanger 4 c. Otherstructures are the same as those in FIG. 7.

In the fifth modification, the plate fins 1 of the lower front heatexchanger 4 a, the upper front heat exchanger 4 b, and the rear heatexchanger 4 c are provided with the louvered portions 3, and the heightSa of the louvered portions 3 of the plate fins 1 in the lower frontheat exchanger 4 a is smaller than the heights Sb and Sc of the louveredportions 3 of the plate fins 1 in the upper front heat exchanger 4 b andthe rear heat exchanger 4 c. Therefore, the pressure loss caused by airflow through the lower front heat exchanger 4 a is smaller than thatthrough the upper front heat exchanger 4 b and the rear heat exchanger 4c, and the velocity of the air passing through the lower front heatexchanger 4 a increases. Consequently, advantages similar to those ofthe heat exchanger 4 shown in FIG. 1 can be provided.

The velocity of the air passing through the lower front heat exchanger 4a is further increased by making both the settings shown in FIGS. 8A to8C and 9A to 9C for the plate fins 1.

FIG. 10 is a cross-sectional view of an indoor unit as a sixthmodification of the first embodiment. FIGS. 11A, 11B, and 11C aresectional views of a heat exchanger shown in FIG. 10, respectively,taken along lines A-A, B-B, and C-C.

In the sixth modification, the plate fins 1 shown in FIG. 8 are used inthe heat exchanger of the third modification shown in FIG. 6.

That is, at the lowermost end of each plate fin 1 in a lower front heatexchanger 4 a, a louvered portion 3 is provided only on the mostdownstream side in the louver pitch direction. The upstream portion ofthe plate fin 1 is flat. Plate fins 1 in an upper front heat exchanger 4b and a rear heat exchanger 4 c are provided with louvered portions 3.The fin pitch ha between the plate fins 1 in the lower front heatexchanger 4 a is set to be longer than the fin pitches hb and hc betweenthe plate fins 1 in the upper front heat exchanger 4 b and the rear heatexchanger 4 c. In this case, the pressure loss caused by air flowthrough the lower front heat exchanger 4 a is smaller than that throughthe upper front heat exchanger 4 b and the rear heat exchanger 4 c, andthe velocity of the air passing through the lower front heat-exchangingsection 4 a increases. Consequently, advantages similar to those of theheat exchanger 4 shown in FIG. 1 can be provided.

FIG. 12 shows an indoor unit according to a seventh modification of thefirst embodiment. This is obtained by modifying the heat exchanger 4 ofthe indoor unit shown in FIG. 1. In the seventh modification, a lowerfront heat exchanger 4 a is provided with louvered portions 3, in amanner similar to that in the other heat exchanger 4 b and 4 c. Anauxiliary heat exchanger 4 f is provided on the air upstream side of thelower front heat exchanger 4 a. A space 20 through which air passes isprovided between a front panel 8 and a condensed-water receiver 19.

While the addition of the auxiliary heat exchanger 4 f increases thepressure loss on the lower front side of the indoor unit, the windvelocity on that side increases because air flows in not only from anupper grille 7, but also from the space 20 between the front panel 8 andthe condensed-water receiver 19. Consequently, advantages similar tothose of the heat exchanger 4 of the first embodiment shown in FIG. 1can be provided.

FIG. 13 shows an indoor unit according to an eighth modification of thefirst embodiment. In the eighth modification, an auxiliary heatexchanger 4 e is added on the upstream side of the rear heat exchanger 4c in the seventh modification shown in FIG. 12. In this case, advantagessimilar to those of the heat exchanger 4 in the seventh modificationshown in FIG. 12 can be provided.

FIG. 14 shows an indoor unit according to a ninth modification of thefirst embodiment. In the ninth modification, the auxiliary heatexchanger 4 f is not provided on the lower front heat exchanger 4 a asshown in FIG. 12, and only an auxiliary heat exchanger 4 e is providedon the upstream side of the rear heat exchanger 4 c. In this case, thewind velocity at the lower front heat exchanger 4 a further increases,and advantages similar to those of the heat exchanger 4 in the seventhmodification shown in FIG. 12 can be provided.

FIG. 15 shows an indoor unit according to a tenth modification of thefirst embodiment shown in FIG. 1. In the tenth modification, louveredportions 3 of plate fins 1 in a lower front heat exchanger 4 a, whichare provided closest to a circulating fan 5 and on the most downstreamside in the row direction, are shaped like a parallelogram havingopposite sides inclined downward at an angle θ to the row direction. Theother louvered portions 3 are trapezoidal.

When all the louvered portions 3 of the lower front heat exchanger 4 aare trapezoidal, as shown in FIG. 16A, air passing through the lowerfront heat exchanger 4 a travels straight toward the circulating fan 5in the row direction. Consequently, a separation vortex 14 is producedon an inner pressure surface of the circulating fan 5, and the input tothe circulating fan 5 increases.

In contrast, when the louvered portions 3 of plate fins 1 in the lowerfront heat exchanger 4 a, which are provided closest to the circulatingfan 5 and on the most downstream side in the row direction, are shapedlike a parallelogram having opposite sides inclined downward at theangle θ to the row direction, air passing through the lower front heatexchanger 4 a travels downward toward the circulating fan 5, andsubstantially follows the attack angle of blades in the circulating fan5 as shown in FIG. 16B. Consequently, no separation vortex is producedon the pressure surface, and the input to the circulating fan 5decreases.

FIG. 17A is a partial cross-sectional view showing the vicinity of anupper contact portion between an upper front heat exchanger 4 b and arear heat exchanger 4 c in a heat exchanger of a conventional indoorunit. A front surface of the indoor unit has a grille 7 through whichair flows.

In the heat exchanger 4 of the conventional indoor unit, the upper frontheat exchanger 4 b and the rear heat exchanger 4 c are in line contactwith each other, and a sealing member 16 is frequently used to prohibitair from passing through the contact portion in order to prevent the airfrom being concentrated near the contact portion without passing throughthe heat exchanger. In this case, the air completely flows around thesealing member 16. Therefore, there is a possibility that the heattransfer area will decrease, that the pressure loss will increase, andthat the fan input will increase.

In contrast, in the indoor units according to the present invention, anend face 35 of the upper heat exchanger 4 b and a side face 36 of therear heat exchanger 4 c are in face contact, as shown in FIG. 17B. Sinceair also flows through the contact portion between the heat exchangers 4b and 4 c, the pressure loss is smaller than in the conventional heatexchanger, and the heat transfer area is not reduced.

In addition, since air does not flow through the panel 8, the windvelocity near the contact portion between the upper front heat exchanger4 b and the rear heat exchanger 4 c is much higher than in the casewhere a grille through which air flows is provided on the front side.Therefore, the above-described advantages are improved.

Such an upper contact between the upper front heat exchanger 4 b and therear heat exchanger 4 c can also be applied to the above-describedstructures (counter measures) for reducing the air pressure loss of thelower front heat-exchanging section 4 a.

Second Embodiment

FIG. 18 is a circuit diagram of a refrigerant circuit in an airconditioner having the above-described heat exchanger of the firstembodiment of the present invention.

The refrigerant circuit includes a compressor 26, a condensing heatexchanger 27, a throttle 28, an evaporating heat exchanger 29, and a fan30. The energy efficiency of the air conditioner can be enhanced byapplying the heat exchanger of the first embodiment to the condensingheat exchanger 27, the evaporating heat exchanger 29, or both thereof.

Herein, the energy efficiency is given by the following expressions:Heating energy efficiency=performance of indoor heat exchanger(condenser)/total inputCooling energy efficiency=performance of indoor heat exchanger(evaporator)/total input

The above-described advantages of the heat exchanger 4 in the first andsecond embodiments and the air conditioner using the heat exchanger 4can be achieved with any of refrigerants, for example, HCFC (R22), HFC(R116, R125, R134a, R14, R143a, R152a, R227ea, R23, R236ea, R236fa,R245ca, R245fa, R32, R41, RC318, or a mixture of some of theserefrigerants such as R407A, R407B, R407C, R407D, R407E, R410A, R410B,R404A, R507A, R508A, or R508B), HC (butane, isobutane, ethane, propane,propylene, or a mixture of some of these refrigerants), a naturalrefrigerant (air, carbon dioxide, ammonia, or a mixture of some of theserefrigerants), and a mixture of some of the above refrigerants.

While air and the refrigerants are exemplified as the working fluid,similar advantages can be obtained with other gases, liquids, andgas-liquid mixtures.

While the plate fins 1 and the heat transfer tubes 2 are frequently madeof different materials, they may be made of the same material such ascopper or aluminum. In this case, the plate fins 1 and the heat transfertubes 2 can be brazed. This dramatically increases the contact heattransfer coefficient therebetween, and greatly enhances the heatexchange performance. Moreover, recyclability is enhanced.

When the plate fins 1 are closely bonded to the heat transfer tubes 2 byfurnace brazing, they are coated with a hydrophilic material afterbrazing. This prevents the hydrophilic material from being burnt duringbrazing.

Furthermore, the heat transfer performance can be enhanced by applying aheat-radiating coating, which promotes radiant heat transfer, onto theplate fins 1.

The above-described advantages of the heat exchanger 4 in the first andsecond embodiments and the air conditioner using the heat exchanger 4can be achieved with any refrigeration oil, such as mineral oil,alkylbenzene oil, ester oil, ether oil, or fluorine oil, regardless ofwhether the oil can mix the refrigerant.

1. plate fin

2. heat transfer exchanger

3. louvered portion

4. (4 a, 4 b, 4 c) heat exchanger

-   -   4 a lower front heat exchanger    -   4 b upper front heat exchanger    -   4 c rear front heat exchanger    -   4 f auxiliary heat exchanger

5. circulating fan

6. air passage

7. air inlet

17. air outlet

20. space

35. end face

36. side face

1. An indoor unit of an air conditioner, comprising: an air inlet; aplurality of fin-tube type heat exchangers each having heat transfertubes extending through stacked plate fins; a fan; an air passage; andan air outlet, wherein the plurality of fin-tube type heat exchangersare arranged to surround the fan, and the air pressure loss of anadjacent heat exchanger disposed adjacent to the air inlet, of thefin-tube heat exchangers, is larger than the air pressure loss of aremote heat exchanger that is disposed farther from the air inlet thanthe adjacent heat exchanger.
 2. The indoor unit according to claim 1,wherein the air inlet is provided on an upper side of the indoor unit,the adjacent heat exchanger consists of an upper front heat exchangerprovided in an upper front area below the air inlet and slightly tiltedso as to make its upper portion positioned backward and its lowerportion positioned forward, and a rear heat exchanger provided in anupper rear area below the air inlet and slightly tilted so as to makeits upper portion positioned forward and its lower portion positionedbackward, and the remote heat exchanger consists of a lower front heatexchanger provided in a lower front area to substantially verticallyextend from the upper front heat exchanger.
 3. The indoor unit accordingto claim 1, wherein each of the plate fins in the adjacent heatexchanger has louvered portions, and each of the plate fins in theremote heat exchanger does not have a louvered portion.
 4. The indoorunit according to claim 1, wherein each of the plate fins in theadjacent and remote heat exchangers has louvered portions, but at thelowermost end portion of each plate fin in the remote heat exchanger, alouvered portion is provided only on the most downstream side in a rowdirection.
 5. The indoor unit according to claim 1, wherein each of theplate fins in the adjacent and remote heat exchangers has louveredportions, but in the louvered portions, of the louvered portions of theplate fins in the remote heat exchanger positioned nearest to the fan,the louvered portions positioned on the most downstream side in a rowdirection are shaped like a parallelogram having opposite sides inclineddownward at a predetermined angle to the row direction.
 6. The indoorunit according to claim 1, wherein the pitch of the plate fins in theadjacent heat exchanger is smaller than the pitch of the plate fins inthe remote heat exchanger.
 7. The indoor unit according to claim 1,wherein the height of the louvered portions in the remote heat exchangeris smaller than the height of the louvered portions in the adjacentheat-exchanging section.
 8. An indoor unit of an air conditioner,comprising: an upper air inlet; a plurality of fin-tube type heatexchangers each having heat transfer tubes extending through stackedplate fins having louvered portions; a fan; an air passage; and an airoutlet, wherein the plurality of fin-tube type heat exchangers includean adjacent heat exchanger disposed adjacent to the air inlet and aremote heat exchanger disposed farther from the air inlet than theadjacent heat exchanger, the adjacent and remote heat exchangerssurround the fan, an auxiliary heat exchanger is provided on an airupstream side of the remote heat exchanger, and a space is provided in afront panel of the auxiliary heat exchanger to pass air therethrough. 9.The indoor unit according to claim 8, wherein the adjacent heatexchanger consists of an upper front heat exchanger provided in an upperfront area below the air inlet and slightly tilted so as to make itsupper portion positioned backward and its lower portion positionedforward, and a rear heat exchanger provided in an upper rear area belowthe air inlet and slightly tilted so as to make its upper portionpositioned forward and its lower portion positioned backward, and theupper front and rear heat exchangers have the same shape, and areconnected so that an end face of one of the upper front and rear heatexchangers is in face contact with a side face of the other heatexchanger near the upper air inlet.
 10. The indoor unit according toclaim 1, wherein the adjacent heat exchanger consists of an upper frontheat exchanger provided in an upper front area below the air inlet andslightly tilted so as to make its upper portion positioned backward andits lower portion positioned forward, and a rear heat exchanger providedin an upper rear area below the air inlet and slightly tilted so as tomake its upper portion positioned forward and its lower portionpositioned backward, and the upper front and rear heat exchangers havethe same shape, and are connected so that an end face of one of theupper front and rear heat exchangers is in face contact with a side faceof the other heat exchanger near the upper air inlet.
 11. The indoorunit according to claim 2, wherein each of the plate fins in theadjacent heat exchanger has louvered portions, and each of the platefins in the remote heat exchanger does not have a louvered portion. 12.The indoor unit according to claim 2, wherein each of the plate fins inthe adjacent and remote heat exchangers has louvered portions, but atthe lowermost end portion of each plate fin in the remote heatexchanger, a louvered portion is provided only on the most downstreamside in a row direction.
 13. The indoor unit according to claim 2,wherein each of the plate fins in the adjacent and remote heatexchangers has louvered portions, but in the louvered portions, of thelouvered portions of the plate fins in the remote heat exchangerpositioned nearest to the fan, the louvered portions positioned on themost downstream side in a row direction are shaped like a parallelogramhaving opposite sides inclined downward at a predetermined angle to therow direction.